Individuals who have experienced early life stress (ELS) are more vulnerable to later life stress induced depression, which might attribute to ELS potentiated impact of later life stress. The presumption and neurobiological mechanisms involved require further validation and elucidation. To investigate impact of pre-weaning maternal separation (MS) on post-weaning social isolation (SI) in inducing depressive-like behavior, and involvement of central oxidative stress, glutamatergic and brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) signaling in the process. Male offspring were exposed to MS, SI or maternal separation and social isolation (MSSI) stress, respectively. Subjects were treated with saline, antioxidant diallyl disulfide (DADS) (30 mg/kg, i.g.) or antidepressant fluoxetine (10 mg/kg, i.p.), for two weeks before behavioral tests in adolescents or adults. Depressive-like behavior was assessed with sucrose preference, forced swim and tail suspension tests. Concentrations of 4-hydroxynonenal (4-HNE), glutathione and superoxide dismutase in hippocampus and serum, and hippocampal protein expressions of glutamate transporter 1 (GLT-1), BDNF and TrkB were assessed by western blotting analysis. MSSI, rather than MS or SI, induced significant depressive-like behavior, in adults but not adolescents. Consistently, only MSSI significantly elevated 4-HNE, whereas inhibited GLT-1, BDNF and TrkB in adult hippocampus. MSSI induced behavioral and biochemical abnormalities in adults were reversed by DADS or fluoxetine treatment. Early MS age-dependently potentiates later SI impact in inducing depressive-like behavior in male rats, through elevating oxidative stress and interrupting glutamatergic and BDNF/TrkB signaling in the brain. Results further suggest antioxidant treatment as a promising anti-depressant avenue.

抑郁症是影响范围广、人数多的精神/心境障碍,其经典致病机制假说包括HPA(hypothalamic-pituitary-adrenocortical axis)轴功能异常、单胺类和神经可塑性缺陷等.要充分阐明抑郁症多种致病因素,及不同病因之间复杂的相互作用关系,仍需更加深入的研究.慢性应激是抑郁症主要临床诱因,利用此动物模型可充分揭示发病过程中复杂的病理机制及其变化趋势,且利于将转化医学研究结果快速有效地向临床转化,对疾病预防和治疗有重要意义.目前现有相关综述主要围绕经典的HPA轴异常、单胺类和神经可塑性缺陷、大脑神经元结构功能、中枢神经递质和因子及其受体等方面异常展开.本文综述了近年抑郁症研究热点和新发现,包括基因变异和表观遗传修饰、神经胶质细胞(星形胶质细胞和小胶质细胞)结构功能异常、线粒体功能障碍、机体系统水平异常(氧化应激、免疫炎症反应和微生物-肠-脑轴),旨在系统呈现慢性应激诱导动物抑郁样行为机制研究进展,为后续有针对性地深入研究致病机制,及其临床预防和治疗提供新思路.

Depression increasingly affects a wide range and a large number of people worldwide, both physically and psychologically, which makes it a social problem requiring prompt attention and management. Accumulating clinical and animal studies have provided us with substantial insights of disease pathogenesis, especially central monoamine deficiency, which considerably promotes antidepressant research and clinical treatment. The first-line antidepressants mainly target the monoamine system, whose drawbacks mainly include slow action and treatment resistant. The novel antidepressant esketamine, targeting on central glutamatergic system, rapidly and robustly alleviates depression (including treatment-resistant depression), whose efficiency is shadowed by potential addictive and psychotomimetic side effects. Thus, exploring novel depression pathogenesis is necessary, for seeking more safe and effective therapeutic methods. Emerging evidence has revealed vital involvement of oxidative stress (OS) in depression, which inspires us to pursue antioxidant pathway for depression prevention and treatment. Fully uncovering the underlying mechanisms of OS-induced depression is the first step towards the avenue, thus we summarize and expound possible downstream pathways of OS, including mitochondrial impairment and related ATP deficiency, neuroinflammation, central glutamate excitotoxicity, brain-derived neurotrophic factor/tyrosine receptor kinase B dysfunction and serotonin deficiency, the microbiota-gut-brain axis disturbance and hypothalamic-pituitary-adrenocortical axis dysregulation. We also elaborate on the intricate interactions between the multiple aspects, and molecular mechanisms mediating the interplay. Through reviewing the related research progress in the field, we hope to depict an integral overview of how OS induces depression, in order to provide fresh ideas and novel targets for the final goal of efficient treatment of the disease.

Studies have shown that both aging and dopaminergic dysfunction affected spatial learning and memory. Systematic dopaminergic inhibition, by dopamine receptor (DR) antagonist treatment, impaired spatial delayed-response (SDR) performance, which mostly requires self/body centered egocentric reference frame, in rhesus monkeys. However, the influence of DR blocking on large scale maze learning, which mainly involves world centered allocentric reference frame, remains unclear. Moreover, the effects of aging on the process also remain unknown. Present study investigated the issues, using large scale mazes composed of 8 maze units. Maze No. 1 was used for adaptation and training. Mazes No. 2-4 were used to investigate influence of aging, by comparing learning performance between young and aged rhesus monkeys. Mazes No. 5-8 were used to investigate the effects of DR antagonist treatment, SKF-83566 (0.02, 0.2 mg/kg) and haloperidol (0.001, 0.01 mg/kg). The result showed similar learning performance between young and aged monkeys in mazes No. 2-4. In mazes No. 5-8, we also found similar learning performance after acute DR antagonist injection, compared with pre-treatment baseline performance in mazes No. 2-4, in both young and aged groups. The result showed similar maze learning performance between young and aged monkeys in mazes (No. 2-4), suggesting no significant influence of aging on allocentric spatial learning. We also found similar maze performance in both groups, after dopamine receptor antagonist treatment in mazes (No. 5-8) compared with pre-treatment baseline performance in mazes (No. 2-4), suggesting no significant influence of dopaminergic inhibition on allocentric spatial learning. Together, the present study potentially suggested insensitivity of allocentric spatial learning to cognitive aging and acute systematic dopaminergic inhibition.

目的:研究锌指转录因子Slug、上皮-间质转化标志物E-钙黏蛋白(E-cadherin)及 β-连环素(β-catenin)在子宫内膜异位症(Endometriosis,EMs)中的表达水平及其意义.方法:选取30例EMs患者的在位内膜及异位内膜作为实验组,选取同时期30例子宫肌瘤患者的子宫内膜作为对照组,采用免疫组化法检测Slug、E-cadherin及β-catenin在实验组及对照组中的表达水平.结果:实验组中Slug的阳性表达及β-catenin的异常表达明显高于对照组(P<0.05),实验组异位内膜Slug的阳性表达及β-catenin的异常表达明显高于在位内膜(P<0.05);实验组中E-cadherin的正常表达明显低于对照组(P<0.05),实验组异位内膜E-cadherin的正常表达明显低于在位内膜(P<0.05).E-cadherin的正常表达与Slug的阳性表达及β-catenin的异常表达呈负相关,Slug的阳性表达与β-catenin的异常表达呈正相关.结论:EMs中Slug及β-catenin表达上调、E-cadherin表达下调,提示EMs可能存在EMT现象,且3者可能共同参与了EMs的发生、发展.

RATIONALE:Phencyclidine (PCP) could induce schizophrenia (Sz) like behavior in both humans and animals, therefore, has been widely utilized to establish Sz animal models. It induced cognitive deficits, the core symptom of Sz, mainly through influencing frontal dopaminergic function. Nonhuman primate (NHP) studies demonstrated impaired object retrieval detour (ORD) and spatial delayed response (SDR) task performance by acute or chronic PCP treatment. However, NHP investigations, continually monitoring SDR performance before, during and after PCP treatment, are lacking.OBJECTIVES:Present study investigated the long-term influence of chronic PCP treatment on SDR performance and the possible increase of SDR deficit severity and duration by the incremental dosing procedure in rhesus monkeys.METHODS:SDR task was performed repeatedly up to eight weeks after constant dosing procedure (i.m., 0.3 mg/kg, day 12-25), during which drug effects on locomotor activity and blood cortisol concentration were assessed. Incremental dosing procedure (starting dose 0.3 mg/kg, day 6-19) began five months later.RESULTS:Constant dosing procedure induced differential level of hyperactivity across testing days, without significant influence on blood cortisol concentration. It reduced SDR performance, until occurrence of the first and worst impairment on day 15 and 23 respectively. The impaired performance recovered to pretreatment level over one week after drug cessation. In contrast, incremental dosing procedure impaired SDR performance on the first treatment day, which recovered within treatment period.CONCLUSION:Results suggested increase of SDR deficit severity by repeated PCP administrations, whereas the incremental dosing procedure did not increase SDR deficit severity and duration.

Acute fetal hypoxia (AFH) can elicit postnatal motor deficits and cognitive impairments. To test whether lifelong acclimatization to middle altitude (MA) hypoxia has protective effects on the impairments caused by AFH, ICR mice bred at 1 900 m altitude for 6-7 generations were evaluated under AFH. On gestation day 9 (GD 9), 13 (GD 13) or 17 (GD 17), pregnant mice received a single exposure to acute hypoxia (7% O2, 6 h). Physiological and neurodevelopmental behaviors, motor function (open field), spatial learning and memory (Morris water maze), and anxiety level (elevated plus maze) were examined in the offspring from neonate to adulthood. In the neonatal age, among all the physiological and behavioral landmarks, almost no differences were found in the hypoxia groups. In the juvenile period, no obvious impairments of motor function and anxiety level were found in the hypoxia groups. In the adult period, no obvious impairment of motor function was found in hypoxia groups; Interestingly, AFH groups' offspring showed normal or enhanced long-term spatial memory ability after AFH. These data suggest that AFH cause little abnormalities in the offspring of MA-adapted mice. To further investigate the underlying mechanisms, the neuronal numbers in behavior-related brain areas (accumbens nucleus, basal amygdala and hippocampus) were counted, and the physiological parameters of the blood were measured. The morphological data showed that no obvious neuronal necrosis was found in all hypoxia groups. In addition, blood tests showed that red blood corpuscle count, hemoglobin concentration and hematocrit levels in mice raised at MA were markedly higher in both males and females, compared with controls raised at the sea level. These data suggest that lifelong acclimatization to MA hypoxia has protective effects against development delay, motor deficits and spatial learning and memory impairments induced by AFH, and the protective effects may be due to higher hemoglobin concentration and hematocrit levels in the blood. The findings may provide a better understanding of fetal hypoxia and potential intervention treatments.

Extinction of conditioned fear has been suggested to be a new form of learning instead of erasure of what was originally learned, and the process is NMDA (N-methyl d-aspartate) receptor (NMDAR) dependent. Most of studies have so far revealed the important roles of NMDARs in the amygdala and medial prefrontal cortex (mPFC) in cued fear extinction. Although the ventral hippocampus has intimately reciprocal connections with the amygdala and mPFC, the role of its NMDARs in cued fear extinction remains unclear. The present experiment explored the issue by bilateral pre-extinction microinjection of the noncompetitive NMDAR antagonist MK-801 into the ventral hippocampus. Four groups of rats were given habituation, tone cued fear conditioning, fear extinction training and extinction test. Prior to extinction training, rats received bilateral infusions of either MK-801 (1.5, 3, or 6μg/0.5μl) or saline. Our results showed that MK-801 reduced freezing on the first trial of extinction training with no impact on within-session acquisition of extinction, and that the lower doses of MK-801 resulted in increased freezing on the extinction retrieval test. These findings suggest that ventral hippocampal NMDARs are necessary for the consolidation of tone cued fear extinction.

Drug addicts experience strong craving episodes in response to drug-associated cues. Attenuating these responses using pharmacological or behavioral approaches could aid recovery from addiction. Cue-induced drug seeking can be modeled using the conditioned place preference procedure (CPP). Our previous work showed that conditioned place preference (CPP) can be induced by administration of increasing doses of morphine in rhesus monkeys. Here, we investigated whether expression of morphine-induced CPP can be attenuated by inhibiting activity of insular cortex or by repeated unreinforced exposures to the CPP test. The insula has been demonstrated to be involved in addiction to several drugs of abuse. To test its role in morphine CPP, bilateral cannulae were implanted into the insula in seven adult monkeys. The CPP was established using a biased apparatus by intramuscular injections of morphine at increasing doses (1.5, 3.0 and 4.5mg/kg) for each monkey. After the monkeys established morphine CPP, their insulae were reversibly inactivated by bilateral microinjection with 5% lidocaine (40μl) prior to the post-conditioning test (expression) of CPP using a within-subject design. The microinjections of lidocaine failed to affect CPP expression when compared to saline injections. We subsequently investigated morphine-associated memory during six episodes of CPP tests performed in these monkeys over the following 75.0±0.2months. While the preference score showed a declining trend with repeated testing, morphine-induced CPP was maintained even on the last test performed at 75months post-conditioning. This observation indicated strong resistance of morphine-induced memories to extinction in rhesus monkeys. Although these data do not confirm involvement of insula in morphine-induced CPP, our observation that drug-associated memories can be maintained over six drug-free years following initial experience with morphine has important implications for treatment of drug addiction using extinction therapy.

ABSTRACTIn rodents, a conditioned place preference (CPP) can be induced by morphine. In the current study, we designed a biased place conditioning paradigm to test the rewarding effects of morphine in freely moving rhesus monkeys. Five monkeys were first placed in three serial rooms with the doors open between them for three days. After this habituation period, during which baseline preference for each of the two end rooms was measured, CPP conditioning occurred when the monkeys were injected intramuscularly with morphine at an increasing dose (1.5, 3, 4.5 mg/kg) before they entered the non‐preferred room and on alternate days, with saline before they entered the preferred room. Morphine and saline treatment lasted for six days, respectively. CPP was tested 24 hours after the end of CPP training. The result showed that in all five monkeys, CPP was induced by the morphine treatment. The preference lasted for at least 15.3 ± 1.7 months.

In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments (enriched, social and isolated conditions). After 8 weeks, fear conditioning (characterized by percentage of freezing) was observed and analyzed, and rats' weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that: (1) Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; (2) Enriched and isolated conditions influenced rat's weight significantly; (3) Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.

Objective To study the impact of two different abstinence periods on locomoter activity in nicotine-dependent rats.Methods Nicotine hydrogen tartrate salt was administrated(sc) to rats at a gradually increasing dose for 14 days to establish nicotine-dependent rats.After the last injection,rats were divided into nicotine group and saline control group;spontaneous activities including the distance,the number of rearing,grooming time,and time spent in center and peripheral area,were observed in the open field box after different periods of abstinence.Results Compared with saline control group,distance(P<0.05),the number of rearing(P<0.001) decreased and grooming time increased(P<0.001) significantly in nicotine withdrawal 1 day group.Conclusion During early period of nicotine abstinence,rats have a decreased spontaneous activity.

Many types of mazes have been used in cognitive brain research and data obtained from those experiments, especially those from rodents' studies, support the idea that the hippocampus is related to spatial learning and memory. But the results from non-human primates researches regarding the role of the hippocampus in spatial learning and memory are controversial and inconsistent with those obtained in rodents. This might be due to the differences of the methods used in non-human primates and rodents. Several kinds of maze models including two-dimensional computerized visual maze models and three-dimensional maze models have been developed for non-human primates, but they all have some defects. Therefore, development of a maze model for non-human primates that is comparable with those used in rodents is necessary to solve the controversy. This paper describes a large-scale, three-dimensional outdoor maze model for non-human primates which can be used to study spatial learning and memory. Monkeys learn to use the maze quickly compared with two-dimensional computerized visual mazes. It has many advantages which could make up the limits of the existing three-dimensional mazes in non-human primates, and can be comparable with radial arm mazes used in rodents. Based on the results, we believe that the new maze model will be valuable in many research areas, especially in studies involving spatial learning and memory in freely moving monkeys.

Objective To study the effect of nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester(L-NAME) on extinction of cued fear. Method Fear conditioning and extinction model was established by electric—foot accompanied with tone,then only tone but no shock.We observe the effects of pre-extinction L-NAME injection on extinction learning and memory abilities. Result The extinction learning and memory of L-NAME injection rats were significantly decreased.Conclusion Nitric oxide synthase inhibitor L-NAME impaires extinction of cued fear.

The responses of sensory neurons to repeated presentations of identical stimuli can be highly reproducible. Little is known about the reliability of the motor command signals carried by individual premotor neurons. We measured the variability in the interspike intervals of the high-frequency, saccade-related bursts generated by neurons in the pontine reticular formation. During movements having similar amplitudes and velocity profiles, the interspike intervals of the high-frequency component of the bursts are very similar. The low variability in interspike intervals cannot be attributed to a burst mode characterized by fixed interspike times. Different, but repeatable, burst patterns are observed when movements having approximately the same amplitude but different velocity profiles occur. These findings suggest that the discharge of a single pontine cell is strongly correlated with the activity of other pontine burst cells. Both the high temporal precision of the saccade-related bursts and the correlated activity of pontine burst cells reduce variability in the signals sent to the motoneuron pools and, thereby, contribute to the accuracy and precision of saccadic eye movements.

Proteins that bind to G protein-coupled receptors have been identified as regulators of receptor localization and signaling. In our previous studies, a cytoskeletal protein, actin-binding protein 280 (ABP-280), was found to associate with the third cytoplasmic loop of dopamine D(2) receptors. In this study, we demonstrate that ABP-280 also interacts with dopamine D(3) receptors, but not with D(4) receptors. Similar to the dopamine D(2) receptor, the D(3)/ABP-280 association is of signaling importance. In human melanoma M2 cells lacking ABP-280, D(3) receptors were unable to inhibit forskolin-stimulated cyclic AMP (cAMP) production significantly. D(4) receptors, however, exhibited a similar degree of inhibition of forskolin-stimulated cAMP production in ABP-280-deficient M2 cells and ABP-280-replent M2 subclones (A7 cells). Further experiments revealed that the D(3)/ABP-280 interaction was critically dependent upon a 36 amino acid carboxyl domain of the D(3) receptor third loop, which is conserved in the D(2) receptor but not in the D(4) receptor. Our results demonstrate a subtype-specific regulation of dopamine D(2)-family receptor signaling by the cytoskeletal protein ABP-280.

This study tested the hypothesis that hypoxia exposure predisposed lung epithelial cells to reactive oxygen species-(ROS) mediated cellular injury. Human lung carcinoma cells (ATCC line H441) having epithelial characteristics (including lamellar bodies, surfactant protein [SP]-A, and SP-B) were cultured in air (air/5% CO 2) or hypoxia (< 1% O 2 /5% CO 2) for 0 to 24 hours before imposition of oxidant stress. Cellular manganese superoxide dismutase (MnSOD) activity (units/mg protein) decreased significantly after 24 hours of hypoxia. In normoxic culture after hypoxia, the cells produced increased ROS, detected as dichlorofluorescein (DCF) fluorescence and H 2 O 2 accumulation in medium. Antioxidants N-acetylcysteine (N-Ac) and ebselen inhibited increased DCF fluorescence after hypoxia. To test their ability to tolerate oxidant stress, some cells were incubated with antimycin A (100 μ M) and trifluorocarbonylcyanide phenylhydrazone (10 μ M) (anti A + FCCP), a mitochondrial complex III inhibitor and respiratory chain uncoupler, which together increase mitochondrial superoxide (O 2 -) and H 2 O 2 production. Lung epithelial cells preexposed to hypoxia released more lactate dehydrogenase (LDH) than normoxic controls in response to increased O 2 - production. Increased LDH release from hypoxia-preexposed cells treated with anti A + FCCP was inhibited by 1 mM N-Ac. Rotenone and myxothiazole increased DCF oxidation more in hypoxic than in normoxic cells, suggesting that mitochondrial electron transport complex I may have been altered by hypoxia preexposure.

The suprachiasmatic nucleus (SCN) controls the circadian rhythm of physiological and behavioural processes in mammals. Here we show that prokineticin 2 (PK2), a cysteine-rich secreted protein, functions as an output molecule from the SCN circadian clock. PK2 messenger RNA is rhythmically expressed in the SCN, and the phase of PK2 rhythm is responsive to light entrainment. Molecular and genetic studies have revealed that PK2 is a gene that is controlled by a circadian clock (clock-controlled). Receptor for PK2 (PKR2) is abundantly expressed in major target nuclei of the SCN output pathway. Inhibition of nocturnal locomotor activity in rats by intracerebroventricular delivery of recombinant PK2 during subjective night, when the endogenous PK2 mRNA level is low, further supports the hypothesis that PK2 is an output molecule that transmits behavioural circadian rhythm. The high expression of PKR2 mRNA within the SCN and the positive feedback of PK2 on its own transcription through activation of PKR2 suggest that PK2 may also function locally within the SCN to synchronize output.

1. Mutations of residues in the third intracellular loops of several G-protein coupled receptors have been shown to confer constitutive activation. The authors investigated the effects of one such mutation in the dopamine D2 receptor.2. Compared to the wild type D2, the mutant D2 receptor (D2T344K) showed a substantial increase in agonist affinity with affinity for antagonists unchanged. The increased agonist affinity was unaffected by pertussis toxin treatment, indicating it is an intrinsic property of the mutant receptor. The potency of dopamine for acute inhibition of forskolin-stimulated cAMP production in stably expressing Chinese Hamster Ovary (CHO) cells was higher for the mutant than the wild type receptor.3. CHO cells stably expressing D2T344K displayed enhanced responses to forskolin-stimulated adenylate cyclase activity compared with cells stably expressing the wild type D2 receptor. The increased forskolin responsiveness of adenylate cyclase is similar to the sensitization previously observed with wild type D2 receptor after agonist treatment. Adenylate cyclase responsiveness of CHO cells stably expressing D2T344K receptor was not further increased by agonist treatment,4. Sensitization was blocked by pertussis toxin and D2 receptor antagonists haloperidol, butaclamol, and clozapine, indicating inverse agonist activity of these compounds at D2T344K. Inverse agonist activity was further demonstrated by the finding that overnight treatment with these compounds drastically increased the density of the mutant receptor but had minimal effect on the density of the wild type receptor.5. Taken together, these results suggest the authors have generated a constitutively active dopamine D2 receptor capable of sensitizing adenylate cyclase in the absence of agonist activation.

Abstract: Genomic and cDNA clones encoding the rat Dl receptor were isolated and sequenced. Comparison of the Dl receptor cDNA and genomic sequences revealed that the rat Dl receptor gene is organized into two exons separated by a small intron in the 5’untranslated region of its mRNA. The transcription start site is located 864 bp upstream from the translational initiation site. The 5′‐flanking sequences of the Dl receptor gene do not contain TATA and CAAT canonical sequences, but have a high G + C content, potential cyclic AMP and glucocorticoid response element sequences, and binding sites for transcription factors such as Sp1, Ap1, and Ap2. Transfection studies using the Dl 5′‐flanking sequence and CAT gene fusion constructs have demonstrated that (1) the D1 promoter is active in Dl‐expressing neuroblastoma NS20Y cells, but inactive in D1‐deficient glioma C6 and kidney 293 cells, (2) the information contained within 735 bp of 5′‐flanking sequence of the Dl gene appears to be sufficient to confer its cell‐specific expression, and (3) the Dl gene promoter responds to cyclic AMP induction, suggesting the existence of an autoregulation mechanism by which the stimulation of Dl receptor exerts a positive feedback on its own gene expression.